Solid-state lighting (SSL) in conjunction with light-emitting diodes (LEDs) has been widely used for room lighting due to the long life time and low power consumption. The alternating current (AC) voltage used in lighting the LEDs, however, due to its sinusoidal characteristic, can cause flickering effects on the LEDs that are uncomfortable to human eyes. For example, when the voltage to the LED falls below a certain value required to turn on the LEDs, the LEDs flicker. To reduce the flickering effects, various approaches have been utilized, trying different techniques. For example, in one approach, extra wiring on the transformer used to convert the AC voltage to the direct current (DC) voltage is used to clamp the AC voltage. In another approach, a charging circuit is used in series with the LEDs to share the output charge and to generate the clamping LED voltage. In another approach, a path parallel with the LEDs that delivers energy to the LEDs is used to generate the clamp voltage for the LEDs. The clamp voltage in those approaches, however, depends on the inductor and the capacitor value used in related circuitry. As a result, the clamp voltage changes when the inductor value and/or the capacitor value changes.
Like reference symbols in the various drawings indicate like elements.